The present invention generally relates to engine fuel systems and, more particularly, to combustible fuel devices that generate combustible vapors such as internal combustion engines.
Heretofore, combustible vapors were directed into the cylinders of internal combustion engines using either carburetors or fuel injectors. Fuel injectors were either continuous or pulsed. The continuous fuel injectors directed the combustible vapor into an intake manifold, and when an intake valve opened, the vapor was drawn into the cylinder by the piston. The pulsed fuel injectors directed fuel vapor on command into either a region upstream of each intake valve or directly into the combustion chambers. Both of these fuel delivery systems are highly developed, well known, and have been in use for decades.
By way of further background, the engine fuel system disclosed in this document also generally relates to a printing/imaging technology known as thermal ink jet or bubble jet. For printing marks and text on various media with water based inks, this technology is likewise well known and highly developed.
As environmental regulations become more and more stringent, there is an increasing need for more precise control of the fuel/air stoichiometry in the combustion chambers of an engine. Several problems continue to persist in conventional fuel delivery technology. For instance, if excessive fuel is used or too little air, the amount of hydrocarbon emissions increases correspondingly. Also, for fuel injectors, the orifices change in size over time; they get larger due to mechanical wear and smaller due to clogging from both the constituents in the fuel and small particles that are not removed by the fuel filter. In addition, the requirement for more precise fuel and air metering to meet environmental and fuel economy regulations has caused both carburetors and fuel injectors to become more and more expensive.
There is also a need for an inexpensive, simple fuel delivery system for small industrial engines, those having about twenty-five horsepower or less. These are the engines used on lawn mowers, rotary tillers, outboards, and scooters, for example. These engines are increasingly being subject to environmental regulation, but it is impractical to incorporate a conventional fuel delivery system that costs as much or more than the rest of the machine.
Further, with these conventional fuel delivery systems, reliability continues to be a problem. For example, a conventional fuel injection system requires high-pressure pumps and carefully engineered fuel conduits, tubing, and connections that must withstand constant vibration and extreme variations in operating temperature.
It is apparent from the foregoing that although there are well-developed engine fuel delivery systems, there is a need for an approach that meets increasingly stringent environmental regulations, is reliable and inexpensive, and more precisely controls the fuel/air stoichiometry in combustion chambers.
Briefly and in general terms, an apparatus according to the invention includes a micro-pump having a housing, a pressure regulator connected to the housing, a combustible liquid inlet conduit in fluid communication with the pressure regulator, and a drop ejector on the housing and in fluid communication with the pressure regulator. The drop ejector contains a nozzle capable of ejecting a combustible liquid in a drop-by-drop fashion from the drop ejector.
Another aspect of the invention is an apparatus for generating a combustible vapor including a micro-pump for ejecting a combustible liquid drop-by-drop therefrom and means, connected to the micro-pump, for channeling a stream of air through the drops ejected by the micro-pump thereby generating a combustible vapor for combustible fuel devices such as an internal combustion engine.
In operation, the apparatus ejects a combustible liquid drop-by-drop from a micro-pump and channels a stream of air through the drops ejected by the micro-pump, thereby generating a combustible vapor.
Other aspects and advantages of the invention will become apparent from the following detailed description, taken in conjunction with the accompanying drawings, illustrating by way of example the principles of the invention.